The present invention relates to a system for transmitting the power of an engine to four wheels of a four-wheel drive vehicle.
In a conventional four-wheel drive vehicle having a central differential, which is called a full time four-wheel drive vehicle, the central differential operates to uniformly distribute the torque of an engine to front wheels and to rear wheels.
It is known that the distribution ratio of torque has influences on driveability, steerability, stability, starting characteristic and others. Namely, when the distribution to the front wheel is increased, a stable cornering characteristic at high vehicle speed is established, and when distribution to the rear wheels is increased, steerability at low vehicle speed is improved. In the conventional four-wheel drive vehicle, the distribution ratio of torque for front wheels to rear wheels can not be changed.